Psychological and pharmacological treatments of intermittent explosive disorder: a meta-analysis protocol

Abstract

Introduction Intermittent explosive disorder (IED) is characterised by recurrent, sudden episodes of impulsive aggression that are disproportionate to the provocation. The condition’s management remains challenging due to the variability in treatment efficacy and the absence of Food and Drug Administration-approved interventions specifically for IED. This meta-analysis aims to evaluate the effectiveness of existing treatments for IED.

Methods and analysis Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a comprehensive literature search was conducted in November 2023, yielding 17 randomised controlled trials after screening and eligibility assessments. Studies were included based on participants’ confirmed diagnosis of IED, sufficient statistical power and provision of data for effect size calculation. Interventions analysed included pharmacological treatments, psychotherapies and combination therapies, with an emphasis on cognitive–behavioural therapy and selective serotonin reuptake inhibitors. Quality assessment was performed using the Cochrane Risk of Bias Tool.

Ethics and dissemination Given that our study is a synthesis of published data, ethical approval from a research ethics committee is not required. Nevertheless, the methodology of this review was designed to ensure full transparency and accountability. All efforts have been made to respect the confidentiality and intellectual property rights of the original data sources. Any ethical issues encountered during the data collection process were addressed in accordance with the guidelines of the Declaration of Helsinki. As this research involves the analysis of existing published data, there are no direct safety concerns related to patient interactions. Our primary focus has been on ensuring the secure handling and processing of data to uphold the ethical standards set by previous original studies. To ensure the findings of our meta-analysis reach both the academic community and the public effectively, we aim to submit our findings to peer-reviewed journals within the fields of psychology to ensure rigorous review and broad academic dissemination.

PROSPEO registration number CRD42024497587.

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STRENGTHS AND LIMITATIONS OF THIS STUDY

• Inclusion of randomised controlled trials (RCTs): By focusing exclusively on RCTs, the strongest level of evidence for therapeutic interventions is considered, which strengthens the validity of the results and conclusions drawn.

• Consideration of comorbidities: Including studies where participants have comorbid conditions like depression reflects the real-world complexity of intermittent explosive disorder, making the findings more applicable to typical clinical populations.

• Potential for publication bias: Despite efforts to mitigate this, the possibility of publication bias, as suggested by the funnel plot analysis, may still skew the results.

• Heterogeneity of studies: Variability in terms of interventions, outcome measures and participant characteristics across studies can make it challenging to draw definitive conclusions about the effectiveness of treatments.

Introduction

Intermittent explosive disorder (IED) is characterised by sudden and disproportionate outbursts of anger in response to minor daily provocations.1 These outbursts can manifest as verbal aggression (eg, temper tantrums, tirades and arguments) or physical aggression towards the property, animals or other individuals.2 These angry outbursts are often spontaneous and not premeditated. After the outburst, the individual may feel remorse, regret or embarrassment about their actions.1

The global prevalence of IED is estimated to be between 4% and 6%, depending on the diagnostic criteria used.1 3 Notably, there has been a rise in IED diagnoses over the past decade,3 4 possibly attributed to changes in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) diagnostic criteria,2 5 which now include verbal aggression as an important diagnostic criterion for IED.2 3 This diagnostic criteria adjustment may have led to an increased number of individuals meeting the criteria for IED.6 Furthermore, the overlap between IED and other mental health disorders has historically been a challenge in diagnosis. However, as understanding of comorbidities grows and clinicians become more adept at identifying multiple disorders, there has been an increase in diagnosing IED, especially in cases where it coexists with other disorders.7

Among the psychiatric disorders that exhibit the highest comorbidity with IED are mood disorders (such as major depressive disorder and bipolar disorder), anxiety disorders (including generalised anxiety disorder and panic disorder) and substance use disorders.8 The presence of these comorbid conditions complicates the clinical picture and influences treatment outcomes. For instance, individuals with both IED and a mood disorder may exhibit more severe symptoms and have a poorer prognosis compared with those with IED alone.9

Behavioural issues associated with IED may improve with age,3 For instance, aggressive behaviours, both physical and verbal, tend to decrease as individuals mature. This improvement can be attributed to several key factors. First, developmental changes in emotional regulation play a crucial role. As individuals age, their brains become more adept at managing emotions and controlling impulses, leading to fewer aggressive outbursts and better handling of agitation.10 Second, socialisation processes significantly contribute to this decline. Increased social interactions and experiences help individuals understand and adhere to social norms, thereby reducing aggressive behaviours.11

However, adolescents with IED are still at a higher risk of social difficulties, academic underperformance and criminal behaviour.12 13 Although aggressive behaviour is widespread and the DSM-5-TR recognised IED as a disorder primarily characterised by impulsive aggression,5 there are currently no interventions approved by the US Food and Drug Administration specifically for reducing these behaviours.4 Current treatment options for IED are diverse, yet their efficacy varies and is not universally established due to the complexity of the disorder.14–16

Psychotherapy, especially cognitive–behavioural therapy (CBT), is often the primary treatment for IED.14 17 18 CBT is a structured, goal-oriented therapy that involves working with a therapist to understand how thoughts affect actions, aiming to change negative thought patterns and behaviours to healthier ones.18 Specific techniques used in CBT for IED include cognitive restructuring, relaxation training, coping skills training and relapse prevention.14 17 18 These techniques are designed to help individuals with IED manage negative situations in daily life and prevent aggressive impulses that can trigger explosive outbursts.

Regarding pharmacological treatments, certain medications can increase the threshold at which situations trigger angry outbursts in people with IED.19 Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is the most studied medication for treating IED.3 4 6 13 19 Other medications that have shown promise in treating IED include phenytoin, lithium, oxcarbazepine and carbamazepine.20

Despite these options, a critical gap remains in the systematic evaluation and comparison of these treatments. Conducting a meta-analysis in this field is, therefore, essential as it would provide a more comprehensive understanding of the effectiveness of current treatments by aggregating data from multiple studies. This aggregated analysis could identify the most effective interventions, inform better practices and guide future research directions for IED. This study aimed to perform a comprehensive meta-analysis to evaluate the effectiveness of various treatments for IED. It specifically aimed to compare these treatments’ efficacy against waitlist and placebo controls, examine differences in attrition rates, assess the durability of treatment gains at follow-up and identify emerging promising treatments for IED.

Method

Discussion

To the best of our knowledge, this is the most up-to-date and comprehensive review focusing on current studies targeting treatments specifically for IED. Unlike individuals influenced occasionally by general aggressiveness or impulsiveness, individuals with IED exhibit more complex symptoms and endure the disorder for a longer period. However, the management of IED presents a significant challenge due to its complex aetiology and the variability in patient response to treatment. Therefore, this meta-analysis aims to synthesis existing research on the psychological and pharmacological treatments of IED to identify the most effective therapeutic modalities. By adopting a protocol that meticulously compares the efficacy of treatments against control conditions, this study addresses a critical gap in the literature and provides a systematic evaluation of current interventions.

The findings of this meta-analysis are expected to highlight the relative strengths of CBT, which remains a cornerstone in the psychological treatment of IED. Our results are expected to align with existing literature that consistently supports CBT’s effectiveness in managing IED symptoms. Studies such as Coccaro et al and McCloskey et al have shown significant reductions in aggressive outbursts through CBT interventions. The structured approach of CBT, with its emphasis on understanding and modifying thought patterns and behaviours, is anticipated to be validated as an effective intervention. Moreover, the analysis may also reveal the potential of pharmacological treatments, such as SSRIs, to manage the symptoms of IED, particularly in reducing the frequency and intensity of explosive outbursts. The meta-analysis is also expected to shed light on how these comorbid conditions, such as mood and anxiety disorders, influence the treatment trajectory of IED. This insight can guide clinicians in creating comprehensive, personalised treatment plans that address the multifaceted nature of the disorder.

The limitations of the current meta-analysis will also be acknowledged, including potential publication bias and the inclusion of studies with diverse methodologies. For instance, one of the significant limitations of this meta-analysis and systematic review is the relatively small number of studies included. The limited number of studies may contribute to high heterogeneity, making it challenging to draw consistent and reliable conclusions about the effectiveness of the interventions studied. The limited number of studies qualified was partially due to the fact that IED has only relatively recently been recognised as a distinct psychiatric disorder, and its diagnostic criteria have evolved over time. However, awareness and understanding of IED among clinicians and researchers have increased only in recent years, leading to a gradual rise in focused research. Such limitations underscore the need for a cautious interpretation of the results and suggest areas for improvement in future research.

In summary, the findings of this study corroborate existing knowledge in the field of IED treatment, the impact of comorbid conditions, and the methodological challenges faced in research. By providing a comparative analysis of psychological and pharmacological treatments, this study aims to inform evidence-based clinical practices and stimulate further research to enhance the quality of care for individuals with IED. To improve treatment for IED, there needs to be increased awareness, better diagnostic tools and more dedicated research into the specific mechanisms of the disorder. Future research should focus on tailoring the development of integrated treatment models to improve treatment outcomes for individuals with IED.

Ethics statements

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